1. Field of the Invention
The present invention relates, in general, to electrical watthour meters and, specifically, to watthour meter mounting enclosures or socket adapters.
2. Description of the Art
Electrical power is supplied to an individual site or service by external electrical power line conductors located above or below ground. In a conventional arrangement, electrical power line conductors are connected to terminals in a watthour meter socket mounted on a building wall. Electrical load conductors are connected to another set of terminals in the meter socket and extend to the electrical distribution network in the building. A watthour meter is connected to both pairs of terminals in the meter socket to measure the electric power drawn through the load conductors.
Due to the current trend toward the use of plug-in watthour meters, A to S type socket adapters have been devised which convert A-base type bottom connected watthour meter sockets to receive plug-in watthour meters. Another type of socket adapter has been devised which allows the installation of other devices between the watthour meter socket and a plug-in watthour meter.
Such socket adapters employ a generally annular base having a shell joined thereto and extending outward from one side of the base. Jaw contacts are mounted in the shell and base. Each jaw contact has a female jaw portion disposed interiorly within the shell and a male blade terminal connected to the female jaw portion and extending outward through the base for plug-in connection to the terminals in the meter socket housing.
In previous watthour meter socket adapters, the jaw contacts were of two different constructions. In one construction, the jaw contacts have a folded over design formed of a base wall fixedly mounted by a fastener to the shell of the socket adapter and two spaced sidewalls extending therefrom. The outer ends of the sidewalls are folded over inwardly between the sidewalls and terminate in parallel end flanges which slidably receive a blade terminal of a watthour meter. A blade terminal is usually fixedly connected to the base wall of the jaw contact for connection to jaw contact in a meter socket.
In the second construction, the jaw contacts are formed of a generally planar terminal having opposed first and second ends. An angularly bent spring clip is riveted at one end to an intermediate portion of the terminal and extends to a contact edge disposed in separable engagement with the first end of the terminal to form a jaw for receiving the blade terminal of a watthour meter. The spring clip forcibly biases the watthour meter terminal into secure electrical engagement with the terminal. The second end of the blade terminal extends exteriorly from the base of the watthour meter socket adapter for releasable engagement in a socket jaw contact. A cotter pin is inserted through an intermediate aperture in the terminal to fixedly mount the terminal and jaw contact in position in the watthour meter socket adapter.
While it is typical for a watthour meter, once it is installed in a socket or socket and socket adapter, to remain in service for many years, it is still necessary for such meters to be removed for repair or replacement from time to time as well as to temporarily disconnect electrical service to a particular customer. During the installation and removal of the watthour meter from the socket or socket adapter, the electric power line terminals in the socket or socket adapter remain connected to the electric utility power line conductors and carry potential. The utility employee installing or removing the watthour meter may inadvertently touch such contacts thereby raising the possibility of injury. Furthermore, an inadvertent short across the contacts caused by a tool contacting the contacts or a full fault caused by a 90.degree. offset insertion of the meter can cause a spark or flash which could damage the watthour meter installation as well as posing a significant risk of injury to the utility employee.
In U.S. Pat. No. 5,577,933, the present Applicants disclosed a unique safety shield for a watthour meter mounting apparatus which completely covered all of the exposed portions of the jaw contacts to prevent inadvertent contact with such contacts by the utility employee or by a tool.
One embodiment of this safety shield was in the form of a housing having a unitary sidewall and top wall defining a closed body with an internal recess surrounding the jaw contacts. Narrow apertures or slots were formed in the top wall for receiving a blade terminal of a watthour meter therethrough into engagement with a jaw contact disposed immediately below the aperture in the top wall of the safety shield. In another embodiment, a plurality of receptacles extend from a planar wall mountable in the socket adapter, with each receptacle having one or more slots for receiving the meter blade terminals therethrough. The individual receptacles were sized to completely surround at one jaw contact in the socket adapter.
In yet another embodiment, front and back plates surround the jaw contacts, conductors and the bottom mounted terminals. The front and back plates are joined by a number of fasteners or screws as well as two clips on the terminal portions of the plates.
The safety shield disclosed in U.S. Pat. No. 5,577,933 has proven to be an effective shield in preventing inadvertent contact with the jaw contacts. However, this safety shield is mounted to the bottom wall of a watthour meter socket adapter by means of fasteners extendable through apertures in the safety shield. This involves an additional assembly step and labor as well as additional components to fixedly mount the safety shield within the socket adapter which increase the cost of the socket adapter.
Thus, it would be desirable to provide an improved safety shield for a watthour meter socket adapter which may be easily mounted in and removed from a watthour meter socket adapter. It would also be desirable to provide an improved safety shield for a watthour meter socket adapter which can be releasibly mounted in a socket adapter by means of a snap-in connection.